Melt butter on medium heat. Pour in chopped pecans and stir well to coat with butter. Continue to heat and stir until pecans are lightly toasted. Set aside to cool slightly (do not let pecans completely cool).
Mix vanilla cake frosting with cream cheese, blending well. Stir in cool whip.
Pour warm pecan and butter mixture over frosting mixture. Stir until well blended. Pour into pie crust. Arrange pecan halves over top of pie as garnish(optional). Refrigerate overnight before serving.